#include<bits/stdc++.h>

using namespace std;

int prime(int n) {
    if (n <= 1)return 0;
    //[2 ,sqrt(n)]
    int m = sqrt(n);
    for (int i = 2; i <= m; i++) {
        if (n % i == 0) {
            return 0;
        }
    }
    return 1;
}

int main() {
    long long start = clock();//1970/1/1
    for (int i = 1; i <= 1000000; i++) {
        if (prime(i)) {

        }
    }
    long long end = clock();
    cout << (end - start) / 1000.0 << endl;
    return 0;
}
